Beginner Help on Materials, Shading, and Textures
A Shader, or BSDF (Bidirectional Scattering Distribution Function), is the math definition for calculating light bounce. Different shaders such as Diffuse and Glossy have different definitions.

Materials are datablocks that can be applied to meshes. Think of it as a real material in the world (like wood).

Textures are images that mostly add photorealism to your mesh. The most common texture maps are


Color or Albedo: The color of the material.
Reflection or Specular: How much light the material reflects.
Glossy or Roughness: How concentrated or diffuse the reflection is (like a mirror vs brick).
Bump or Displacement: A grayscale map used to make the material go up and down with lighter pixels representing higher areas and darker pixels representing lower areas.
Normal: A purple-blue map that defines the direction of displacement.
Ambient Occlusion: This makes lower areas darker.


There are a lot more maps, and you can find definitions about them by googling.